Caseless cartridges having the projectile housed in the propellant charge



Dec. 9, 1-969 FARMER ET AL 3,482,516

CASELESS- CARTRIDGES HAVING THE PROJECTIL'E HOUSED IN THE PROPELLANTCHARGE Filed Dec. 28. 1967 FIG. I

LEONARD J. FARMER F l G. 4 INVENTORS.

ATTORNEY United States Patent CASELESS CARTRIDGES HAVING THE PROJEC-TILE HQUSED IN T HE PROPELLANT CHARGE Leonard J. Farmer and John A.Ruth, Wilmington, Del.,

assignors to Hercules Incorporated, Wilmington, Del.,

a corporation of Delaware Filed Dec. 28, 1967, Ser. No. 694,310 Int. Cl.F42b /18 US. Cl. 102-38 8 Claims ABSTRACT OF THE DISCLOSURE A round ofcaseless ammunition is provided wherein the projectile is completelyhoused within an axial bore in a propellant charge. The primer issecured within the propellant charge in axial alignment with theprojectile.

This invention relates to a round of caseless ammunition in which theprojectile is completely housed in propellant.

Firearm designers have long recognized the advantages of caselessammunition. Caseless ammunition is light in weight and it eliminates theneed for extraction and ejection of spent cartridge cases, making higherfiring rates possible. The problem of disposing of spent cartridge casesis also eliminated. The caseless ammunition of this inventionincorporates the desirable characteristics of caseless ammunitionheretofore described while providing rounds which are very compact andhaving unique outside configurations.

Broadly, in accordance with this invention, there is provided a round ofcaseless ammunition having in combination a projectile, a primer, and apropellant charge having an axial bore. The projectile is housed withinthe axial bore of the propellant charge. The wall of propellant; formedby the axial bore in the propellant charge, surrounds the projectile. Around of caseless ammunition in which the projectile is housed inpropellant as described is referred to hereinafter as a telescopedround. In the telescoped rounds of this invention the entire length ofthe projectile is surrounded by propellant.

The telescoped round of ammunition of this invention offers manyadvantages to firearm designers over both the conventional and caselessammunition known in the prior art. The telescoped round can have variedoutside configurations such as that of a cylinder or a parallelepiped.New and simple chamber designs for single shot and automatic weapons aretherefore possible. The telescoped rounds can be made more compact thanconventional caseless rounds and yet have substantially the sameballistic performance as conventional caseless rounds. The compactnessof the telescoped rounds makes them easy to handle and eliminatespotential operational difiiculties in the gun mechanism.

Various advantages of the invention will become more fully apparent fromthe following description of the drawings, illustrating representativeembodiments of this invention.

FIG. 1 is a vertical section of a longitudinal view of a telescopedround of caseless ammunition.

FIG. 2 is a vertical section of a longitudinal View of anotherembodiment of a telescoped round of caseless ammunition.

. FIG. 3 is a vertical section of a longitudinal view of still anotherembodiment of a telescoped round of caseless ammunition.

FIG. 4 is a vertical section of a longitudinal view of a bolt operatedfirearm loaded with a telescoped round of caseless ammunition.

In FIG. 1 a projectile is housed within the bore 12 of a propellantcharge 14. The projectile 10' is secured at the base 16 of the bore ofthe propellant charge. The propellant charge 14 has an axial recess 17into which a primer 18 is secured. The propellant charge 14 is ignitedby initiation of the primer 18.

FIG. 2 illustrates a slightly dilferent embodiment of a telescoped roundof caseless ammunition. In FIG. 2 the projectile 20 is centered andsecured at the fore end 22 of the bore of the propellant charge 24 by acap 26. The projectile 20 is held in place at the aft end by a plug 28which contains an axial cavity 30. The primer 32 is secured into the aftend of the cavity in the plug. An auxiliary ignition charge 34 is heldin the forward end of the axial cavity in the plug between the aft endof the projectile 20 and the primer 32. Both the cap 26 and the plug 28are adhesively secured to the wall of molded propellant 36 formed by theaxial bore through the propellant charge.

FIG. 3 illustrates a telescoped round of caseless ammunition wherein asubcaliber projectile 38 is secured within the axial bore 40 of thepropellant charge 42 by a sabot 44 and sabot base 46. The round issecured at the forward end by a combustible cap 50. The sabot 44 andsabot base 46 can be prepared from a light weight metal such asaluminum. The sabot 44 can have one or more driving bands 52 to impartspin to the projectile. The sabot 44 and sabot base 46 leave the chamberof the firearm, in which the telescoped round is fired, with theprojectile 38. The sabot 44 and sabot base 46 are prepared in segmentsso that they readily separate from the projectile in flight. The sabot44 and sabot base 46, as described, are often referred to simply as thesabot. The sabot is a thrust transmitting carrier for the projectile. Acombustible plug 54 containing a primer 56 and an auxiliary ignitioncharge 58 is adhesively secured in the aft end of the bore 40 of thepropellant charge 42, and holds the sabot base 46 in position.

FIG. 4 illustrates positioning of a telescoped round 60 in the chamberof a firearm. In FIG. 4 the telescoped round is loaded into the forwardend of the chamber 62 of the firearm. An obturated firing pin 64 housedin an obturated bolt 66 is used to initiate the primer 68.

As illustrated in FIGS. 1-4, the propellant charge of this inventioncontains an axial bore of a length equal to or greater than the lengthof the projectile to be used. The diameter of the bore is substantiallyequal to or greater than the maximum outside diameter of the projectileso that the projectile can be housed within the bore of the propellantcharge. The primer is positioned behind the base of the projectile whenthe projectile is seated within the bore of the propellant charge. Theprimer is in axial alignment with the projectile.

The projectile and the primer can be secured within the propellantcharge by any suitable method. The projectile, for example, can besecured with adhesives alone, or it can be secured by use of a nose capand adhesive in the fore end of the round and by a plug and adhesive inthe aft end. The nose cap and plug are of a slightly smaller diameterthan the diameter of the bore and fit into the bore of the propellantcharge. The nose cap can be made of a readily combustible material suchas Styrofoam. The plug can be made of a readily combustible materialsuch as Styrofoam or it can be made from propellant. The primer can besecured within a recess inthe propellant charge as illustrated in FIG. 1or it can be secured inside a cavity in the plug used to support theprojectile as shown in FIG. 2. It is readily apparent that manyvariations in securing the projectile and the primer within thepropellant charge are feasible. The materials used for this purpose mustbe compatible with the propellant formulation constituting thepropellant charge.

The propellant which can be used to prepare the propellant charge can beof the single base, double base, triple base, or composite typepropellant compositions. The propellant is uitilized in the form ofsmall granules. The propellant charge is generally prepared by mouldingof the propellant to the desired configuration. For example, if a singleor double base composition is chosen for the propellant, it is generallypreferred to prepare the charge by filling a mold with small granules ofpropellant such as smokeless powder granules and adding a binder such asa mixture of collodi-an and acetone. The mold is then pressurized atfrom about 500 p.s.i.-2000 p.s.i. from fractions of a second to about aminute. A propellant charge is recovered from the mold and dried.

The primers which can be empolyed with the telescoped rounds are of thecombustible type and can be prepared, for example, from moldedpropellant filled with a standard priming mixture, and secured to thetelescoped round as desired. The primers can also consist simply of anaxial cavity in the base of the propellant charge or combustible plug,said cavity being filled with a standard priming mixture. The primingmixture is sealed into the cavity provided with a waterproof combustibleseal.

A suitable adhesive for use in securing the projectile and primer in apropellant charge prepared from single base, double base, or triple basepropellant compositions is nitrocellulose dissolved in methyl ethylketone. There are many adhesives that can be used with composite typepropellants. The choice of the adhesive for use with composites willdepend on the binder system employed for the composite propellant.

Table (I) summarizes ballistic results of the firing of telescopedrounds of caseless ammunition. In these tests the projectile was of theconventional 20 mm. type. The propellant charge was prepared from agranular double base propellant. The muzzle velocity and the chamberpressure resulting from the firing are substantially the same as forconventional metal cased rounds.

Ballistic Data irom Firing of Convention Round.

In the firing of a telescoped tround of caseles ammunition theprojectile advances into the barrel of the firearm as a result of theforce delivered to the base of the projectile following initiation ofthe primer. The seating of the projectile in the barrel of the firearmby action of the primer prior to complete initiation of the propellantcharge prevents excessive gas flow ahead of the projectile resulting inballistic performance comparable to that of conventional ammunitionhaving the same weight of propellant charge. It is therefore importantfor optimum performance that the primer be chosen and sized so as tomatch the ignition characteristics of the propellant charge and toprovide enough force to seat the projectile. It is generally desirableto position the primer close to the base of the projectile so that theinitial force resulting from initiation of the primer is not dissipatedin breaking up propellant which can be interposed between the primer andthe base of the projectile as shown in FIG. 1. In a preferred embodimentof this invention the base of the projectile and the primer areconnected by an axial cavity so as to maximize the force at the base ofthe projectile upon initiation of the primer.

It may be desirable in some instances to use an auxiliary ignitioncharge to aid in seating the projectile in the barrel of the firearmprior to complete ignition of the propellant charge. The auxiliaryignition charge consists of small granules of propellant which can beloosely packed in an axial cavity between the base of the projectile andthe primer as illustrated in FIG. 2.

The propellant granules of the auxiliary ignition charge initially havea greater surface area than the propellant constituting the walls of thepropellant charge and consequently are more readily ignited by theaction of the primer. The combined force on the base of the projectileresulting from the initiation of the primer and the auxiliary ignitioncharge aid in seating the projectile in the barrel of the firearm priorto ignition of the entire propellant charge thereby minimizing loss ofenergy.

Suitable materials for use as auxiliary ignition charges include smallgranules of propellant of the same composition as the propellant chargeas well as materials that are more readily ignited than the propellantcharge. Examples of these auxiliary ignition materials include smallgranules of black powder, boron-potassium nitrate and double basesmokeless powder.

The telescoped rounds of caseless ammunition of this invention can beprepared in any size desired. The amount of propellant in the propellantcharge, the caliber of the projectile, and overall round configurationcan be determined by one skilled in the art depending on such factors asthe firearm for which the round is designed, and the desired range forthe projectile.

As will be evident to those skilled in the art, variations andmodifications can be made or followed in light of the foregoingdisclosure and discussion, without departing from the spirit or scope ofthe disclosure, or scope of the claims.

What we claim and desire to protect by Letters Patent 1. A telescopedround of caseless ammunition having in combination a propellant charge,a primer, and a projectile, the propellant charge having an axial boreequal to or greater in length than the length of the projectile, theprojectile being housed completely within the axial bore of thepropellant charge whereby the entire length of the projectile issurrounded by propellant, the primer being positioned behind the base ofthe projectile and in axial alignment therewith, and means for securingsaid primer and projectile within the propellant charge.

2. The telescoped round of caseless ammunition of claim 1 wherein theprojectile is a subcaliber projectile held in a sabot and housed withinthe axial bore of the propellant charge.

3. The telescoped round of caseless ammunition of claim 1 wherein thepropellant charge is prepared from molded granules of smokeless powder.

4. The telescoped round of caseless ammunition of claim 3 wherein theprimer and the base of the projectile are connected by an axial cavity.

5. The telescoped round of caseless ammunition of claim 4 wherein theaxial cavity is filled with an auxiliary ignition charge.

6. The telescoped round of caseless ammunition of claim 5 wherein theauxiliary ignition charge is comprised of small granules of double basesmokeless powder.

7. The telescoped round of caseless ammunition of claim 5 wherein theprojectile and primer are secured within the propellant charge with anadhesive.

'8. The telescoped round of caseless ammunition of claim 5 wherein theprojectile is secured with a combustible cap and combustible plug withinthe axial bore of the propellant charge said propellant charge having aforward end and an aft end, said projectile being secured at the forwardend of the propellant charge with the combustible cap which isadhesively secured to the propell i l cha ge and secured at the aft endof the propellant charge with the combustible plug which is adhesivelysecured to the propellant charge.

References Cited UNITED STATES PATENTS 6 3,345,945 10/1967 Quinlan et a1102-38 3,398,684 8/1968 Kvaule 102-99 X OTHER REFERENCES ShokelessShotgun Powders (S.S.P.); by Wallace Coxe, pub. E. I. du Pont de Nemours& Company, Inc., Wilmington, Del., 1933, p. 7.

ROBERT F. STAHL, Primary Examiner

